Governor for prime movers



P 4 I. M. CRAFTS El AL 5 3.

GOVERNOR FOR PRIME MOVERS Filed Aug. 21, 1936 Patented Apr. 16, 1940 GOVERNOR FOR PRIME MOVERS Irving M. Crafts, Portland, and Charles B. Taylor, Middletown, Conn., assignors to The Pickering Governor Company, Portland, Conn., a corporation of Connecticut Application August 21, 1936, Serial No. 97,150

16 Claims.

Qur invention relates to the class of devices which are employed for the purpose of regulating to a value approximating constant anymeasurable condition or quantity subject to variation,

such condition being found in prime movers and our invention being particularly applicable to overnors therefor, and an object of our invention, among others, is the creation of a device of the type mentioned that shall be particularly eflicient in its operation.

One form of an apparatus embodying the invention, and in the construction and use of which the ObJGCtS. herein set out, as well as others, may' be attained is illustrated in the accompanying drawing in which:

The Figure 1 is a diagrammatic view illustrating our improved governor,

Figure 2 is a view in section on a plane denoted by the dotted line 22 of Figure 1.

Figure 3 is a view in section on a plane denoted by the dotted line 33 of Figure. 1.

It will be readily understood by those skilledpose within the scope of the invention.

While our invention may be applied to various types of prime movers as engines, motors, turbines and the like, in. order to simplify the disclosure we have illustrated our apparatus in connection with an engine which may be of the steam or internal combustion type, and in order to confine the effects of the action of the governor upon theprime mover within minimum limits we introduce relaying, compensating and stabilizing apparatus between the governor and the member, as a throttle, for controlling the operation of the prime mover. In the drawing-herein the numeral 5 denotes a drive shaft having a beveled pinion 6 at its lower end which it will.

be understood is engaged by a driving gear secured to some rotating part of the prime mover which will be hereinafter referred to as an engine. The shaft 5 is mountedinbearings of any suitable construction and ispreferably connected with the governor shaft I by means'of a torsionally flexible drive 8.

The governor proper is of ordinary construcmore fully described in Patent No. 1,674,950, dated tion comprising fly weights 9 which spread outwardly by centrifugal action as the shaft I is rotated. A spring l0 acts upon the fly weights to draw them inwardly in opposition to centrifugal force, and a block II has a vertical move- 1 ment effected by the action of the'fly weights all in such a manner as to provide a: jointless, frictionless, fly ball head construction somewhat as June 26, 1928. m

A differential actuator or relay is located in proximity to the governor proper and comprises a cylinder l2 in which a piston I3 is mounted for reciprocating movement. A valve actuating beam support, rigid with the piston, is mounted for 15 reciprocating movement in the cylinder l2, said support comprising a head l4 projecting out of the cylinder at one end and a stem l5 reduced in size projecting out of the opposite end of the cylinder. A valve chamber is formed in said 5 .support, this chamber comprising a hole extending axially therein with a discharge port 11 ex tending out of the chamber through the stem l5 outside of the cylinder and with an inlet port I6 leading to said chamber on one side of the g5 piston andanother port l6 .leading from said chamber on theopposite side of the piston. 'A valve stem having valves at its opposite ends is located in said chamber, one of thesevalves I8 constituting an exhaust valve to control the port 3 I' l-and the valve l9 at the opposite end constituting an inlet valve which controls the port IS. The exhaust valve I8 is rigidly attached to the block I l of the governor proper, said block therefore actuating the valves to control pressure on j the under side of the piston l3, such pressure being introduced through an inlet tube 20 attached tothe cylinder at one end thereof.

It is here remarked that the pressure surfaces on opposite sides of the piston l3 are different 0 in area, that surface on the lower side of the piston being greater than that on the upper surface thereof.

A valve actuating beam 2| is pivotally mounted between ears extending from the exposed end of 45 the supporting head I4. This beam is pivotally connected with one end of a compensating valve rod to be hereinafter described, the opposite end of said beam resting in contact with a disk at one end of a rod 23 adjustably-secured to the stem of a pilot valve 24. A gear 25 secured to the rod 23 is in mesh with a pinion 26 secured to one end of a shaft mounted in a bearing 21, the opposite end of said shaft having a hand wheel 28 secured thereto as a means for rotating the pinion 26 and gear 25. The hand wheel 23 is located externally toa governor enclosing casing for the mechanism, a fragment I05 of which is shown, and a suitable dial (not shown) is pro-- vided to denote the setting of the adjustment,

ment as bymeans of a pin traveling in a slot in a guide 32 projecting from a valve and piston block 33.

The pilot valve 24 is located in a pilot valve chamber 34 in the Mods, an inlet tube 35 for fluid (as oil) under pressure communicating with the chamber 34. Passages 35- 31 communicate with the chamber 34 and, extend through the block 33 into an actuating piston chamber in said block, said chamber containing an actuating piston 38. The piston 38 has a piston rod 39 extending to a bell crank 40 pivotally mounted as in a support 4| and adapted to be connected in any suitable manner with the valve or other device (as a throttle valve) for controlling the operation of an engine.

In the operation of the structure thus far described, assuming that the parts are in position with the engine and mechanism connected therewith operating at a uniform speed,- and further assuming that the load on the engine is lessened, the engine of course will increase its speed. This will cause the fly weights 9 under the action of centrifugal force to move outwardly and the block consequently to move downwardly. This will cause the exhaust and inlet valves |8|9 to move downwardly, the former uncovering the discharge port I! and the latter closing the inlet port IS in the valve actuating beam support. The pressure being thus released from underneath the piston l3 said piston will move downwardly until the ports in the piston return to the original position relatively to the valves and further movement'of the piston therefore ceases. The described movement of the piston will move the valve actuating beam support comprising the head |4 downwardly by an amount equal to the movement of the valves and effecting downward movement of the left hand end of the beam 2|, the'opposite end of said beam being held stationary. This causes the beam to exert pressure on the disk 22, thereby moving the pilot valve 24 downwardly and opening the passage 36 to pressure from within the chamber 34. This also uncovers the passage" 31 thereby releasing pressure from within the chamber of the actuating piston 38 on the upper side of said piston. The latter is thereby caused to move upwardly rocking the bell crank 40 and effecting closing movementof the throttle by an amount suflicient to reduce the speed of the engine-to the original value under the reduced load condition.

A compensating valve lever 42 is pivotally attached at one end to the piston rod 39 and is supported intermediate its ends on the stem 43 of aconipensating piston 44 mounted in a piston chamber in the block .33. The other end of said lever is pivotally connected with one end of a pilot valve rod 45 having pilot valves 46 and 41 constituting compensating values secured thereto within a pilot valve chamber 49 in a pilot valve sleeve 49 adjustably mounted in an opening ex-- tending through the block 33. The sleeve 49 has ports 505| opening into recesses 52-53 which communicate by passages 5455 with the chamber for the compensating piston 44 and on opposite sides of said piston. An inlet recess 56 in the block 33 communicates by an inlet port 51 with the pilot valve chamber 48 in the sleeve 49. An inlet tube 53 supplies fluid under pressure to the recess 56.

In the operation of this compensating mechanism, as the piston rod 39 moves upwardly to impart closing movement to the throttle valve, as hereinbefore described, the lever 42 rocking on its fulcrum on the end of the stem '43 of the piston 44 which is held against movement, pushes the pilot valve rod 45 downwardly, actuating the compensating valves 46-41 to uncover the ports 50 and 5|, thereby admitting pressure to the under side of the piston 44 and relieving pressure from the upper side thereof.

As the rod 45 moves downwardly its lower end being pivotally connected with the beam 2| rocks said beam on its fulcrum on the head l4, thereby raising the left hand end of the beam and releasing the disk 22. This permits the spring 30 to raise the head 3| and consequently the pilot valves 24, this movement continuing until the valves 24 cover-the ports 36-31, thus stopping furthermovement of piston 38.

Due to the resulting partially closed throttle the speed of the engine will be reduced from its overspeed as caused by the decrease in load. The ports 595| being uncovered due to the downward movement of the pilot valve rod 45 the piston 44 will be caused to move up. This upward movement will cause the valve rod 45 to be lifted until the ports 595| are again covered when further movement of the piston 44 will cease. This restoring movement of the rod 45 will lift the right hand end of the lever 2|.

Due to the new position of the throttle, the speed is now decreasing and the 'upward movement of the head |4 caused thereby together with the upward movement of the rod 45 above described will permit return of the lever 2| to the original or constant speed position without further displacement of the disk 22. In the event of increase of the load on the prime mover the operation above described will be reversed. Should, during the interval of the operation described, the load have been changed, the beam 2| will be caused to move by the fly weights to accord 'with the changed speed, but the action of the compensator will continue until the parts attain their equilibrium, as above described.

The pilot valve sleeve 49 is pivotally attached at its lower end at point 59 to a pilot valve..

sleeve adjusting lever 59 pivotally mounted on an adjustable support 60 and pivotally connected at its end opposite the sleeve with the piston rod 39. The support 50 is carried by an adjusting screw 6|, having a hand wheel til attached thereto, by means of which the support may be moved back and-forth to change the fulcrum of the-lever and thereby vary the extent of movement of the sleeve 49 in the operation of the lever 59 by the piston rod 39.

The hand wheel 5| will be located externally to the governor enlosing casing hereinbefore referred to and a suitable dial (not shown) may be provided to show the setting of the ad- .iustment.

Under ordinary conditions the speed of a governor controlled engine will be greater when the engine is operating without load than it will I as speed drop.

when operating under a partial or full load. For example,-,if the governor is set to provide a speed of 1030 R. P. M. with no load, when ,a full load is placed upon the engine, the speed will lessen to approximately 1000 R. P. M., and this is known The means for adjusting the degree of movement of the sleeve '49 provides for ,obtaining different speed settings from no load stantially coincident with the pivot 60. In such case the speed droop above described will be ina zipreciable. In some cases, however, owing to unavoidable conditions as to engine structure,

load conditions, etc. the speed droop will be greater and to meet such situations the adjustment of the fulcrum for the lever 59 is provided so that the sleeve 49 may be automatically shifted to reduce the unobjectionable speed droop. From this it will be seen that movement of the sleeve 49 is required only in exceptional cases, and as the amount of movement will vary in diflerent instances the adjustment to suit different amounts of movement is provided, and having beenonce made it will be maintained. The supoportilt may be adjusted to produce any desired I degree of movement of the sleeve 49 from zero to the maximum value obtainable with the linkage by the operation of the piston 38, and the speed droop is therefore adjustable within the same range and may be controlled by setting the support by means of the hand wheel 6| so that substantially no speed droop will occur in passing from no load-to partial or full load.

.The description of the operation hereinbefore set out has considered the support 60 to be in a zero position, that is, adjacent the pivotal connection 60, in which position the operation of the piston 38 would have no effect upon the' sleeve 49, thus maintaining the same speed for any throttle postion, regardlessof load imposed on the engine.

In order to control the rate of movement of the compensating piston 44 a timing valve I00 is movably engaged in a hole extending across the passages 54 and 55 in the block 33, this valve having an eccentric portion such that by rotating the valvethe passages maybe constricted or enlarged to vary the rate of flow through the passages 54 and Y55, thereby varying the rate 9f movement of the piston44.

The apparatus herein set forth includes an automatic safety shut down piston 62 located in a chamber 63 in a block 64, said piston being spring actuated downwardly andhaving a stem 65 projecting downwardly in linew ith the stem nected with or comprises the core of'a solenoid.

A governor pressure valve 12 springpr'essed' downwardly is located in agovernor pressure valve chamber 13 in. the block 64 and controls a passage leading to the-chamber 69 and is connected by a passage 14 with a valve chamber I5 in said block. The chamber 15', isf'connected with the source of governor operatingvalve controlling flow-through said port 9|.

liquid pressuretube extending to different parts pressure, hereinafter described, by a-passage 11 and a tube 18. The chamber 15 is separated from another similar chamber 15 by beats 16 and 16 of the valve I6. The chamber 15 is connected by a lubricating pressure inlet 19 with a tube (not herein shown) leading to the pressure lubricating system of the prime mover.

In the operation of the valves hereinbefore just described, the parts being in the positions shown, a free passage exists from the governor pressure system through the block 64 to the shut down piston 62. The solenoid 'Il may be electrically connected by wires with any mechanism being operated by the prime mover controlled by the governor hereinbefore described. With such parts in normal operation the valve 68 will be in the position shown. Should an abnormal condition arise in such mechanism the solenoid will be excited, the,valve will be raised opening the passage 61 to the atmosphere, thereby relieving pressure in the chamber 63. The piston 62 will thereby be forced downwardly by its spring, thereby moving the lever 66 which will operate the stem of the'valve 24, moving said valve downwardly and opening the passage 31 to the atmosphere and the passage 36 to pressure, thereby operating the piston 38 to close the throttle This will permit the piston 62 the engine, the valve 68 remaining in the positionshown during this operation.

Should the pressure in the lubricating system of the prime mover become low such pressure will be reduced in the lubricating pressure inlet 19 opening from the lubricating system and on the upper side of the valve beat 16, thereby permitting the spring to move said valve beat I6 and valve 16 upwardly, and opening the passage 14 and the other passages, as related, to --the atmosphere through-the passage 16 and causing the piston 62 to operate to shut down the engine. 8

f Pressure may comefrom any suitable source,

although a pump is shown in the present; instance, such pump being a gear pump 89 located in a block BI and operated as by means of fluid, as oil, to and from the pump. In the po sition of the valve shown with the pump gears rotating inthe direction indicated by the ar- -rows, the oil will be drawn in, as fromthe tail of the governor pressure system,through an inlet port 84 and passing through the valve will be delivered through an inlet passage 85 to the pump and will be delivered through an outlet passage 96 to-the'valve and through'a port 8'! to a pressure chamber 88. A check valve 89 controls flow through the port 81. 'A relief valve 90 spring pressed in one direction controls a relief port 9| leading from the chamber 88,- said of the governor pressure system leads from the extending to the inlets 29, 35,- and 58, and to such other parts of the structure as may be desired. The branch 93 also extends to the passage I8 by way of an overspeed shut down-valve 94 rotatably mounted in a valve chamber 95 and having an operative geared connection with a finger 96 located in position to be struck by an overspeed trip 91 carried by a disk 98securedto and rotating with the governor shaft 1. The trip is movably mounted on the disk to be actuated by centrifugal force and when an excessive speed exists the trip will be thrown outward far' enough to strike the finger 96 and thereby operate the valve 94 rotating it to close the branch 93 and to open the tube I8 to the atmosphere as through adrain 99 leading from the chamber 95, and as shown in the drawing.

The pressure being thus relieved in the tube 18,

the valve 12 will function to close the throttle dial (not shown) may be provided to show the position of the valve 94.

An adjustment is provided to limit the degree to which the governor may cause the throttle to open, this means comprising a threaded member I02 to which the left hand end of the lever 66, hereinbefore referred to, is attached. The right hand end of said lever is positioned to be engaged by a lug I03 on the piston rod v39 when said rod is moving in a direction to open the throttle. By

means of the threaded member I92 'this point of engagement may be varied so that for any given throttle position the lever 66 will contact the pilot valve 24 when the latter is in position to just cover the ports 36 and 31. By this means the valve 24 is blocked from upward movement which would uncover the ports to cause further opening of the throttle than that for which the adjustment I0 is set.

A hand wheel I64 for operating the screw I02 may be located external to the governor enclosing casing hereinbefore referred to and a suitable dial (not shown) may also be provided to show the setting-of the adjustment. We claim: 1. A governor mechanism including a motor driven centrifugally operated member, a member for controlling supply of an energizing medium to said motor, and a connection between said menibers, said connection including a pressure operated actuating member, a pilot valve for controlling admission of pressure to said actuating member, a pressure actuated relay connected with said centrifugally operated member for actuation thereby and a connection between said relay and pilot valve, said connection including a member connected with said pilot valve for operating it and also connected with said pilot valve for operation thereby.

2. A governor mechanism including a motor driven centrifugally operated member, a member for controlling supply of an energizing medium tosaid motor, anda connection between said members, said connection including a relay comprising a cylinder, a piston located in said cylinder and having a greater pressure area on one side than on the other and also containing a chamber, ports leading laterally from said chamber to opposite sides of said piston; a double acting valve located in said chamber to control flow through said ports, and an operativeconnection between said valve and said centrifugally operated member.

3. A governor mechanism including a motor driven centrifugally operated member, a member for controlling supply of an energizing medium to said motor, and a connection between said members, said connection including a pressure operated actuator, a pilot valve for controlling admission of pressure to opposite sidrs of said actuator, a disk rigidly supported by said pilot valve, a relay including a pressure actuated piston operatively connected with said centrifugally operated member, and a beam pivotally carried by said relay and having one end loosely engaged with one side of said disk for movement of the beam independently of" the disk, and a connection between said actuator and said beam to effect said independent action.

4. A governor mechanism including a motor driven centrifugally operated member, a member for controlling supply of an energizing medium to said motor, and a connection between said members, said connection including a pressure operated actuator, a pilot valve for controlling admission of pressure to opposite sides of said actuator,

a disk carried by said pilot valve, a relay comprising a cylinder, a piston located in said cylinder and comprising an enlarged head projecting out of one end thereof and a reduced stem projecting out of the other end, said piston having a chamber with ports opening therefrom to opposite sides thereof, a valve located in said chamber and operatively connected with said centrifugally operated member, and a beam pivotally supported by said head and having one end adapted to'rest loosely engaged with one side of said disk for movement of the beam independently of the disk, and a connection between said actuator and beam to eiiect-said independent action.

5. A governor medianism including a motor driven centrifugally operated member, a member for controlling supply of an energizing medium to said motor, and a connection between said mem; bers, said connection including loosely. disengageable members operating independently of each other and a pressure operated actuating piston; a pressure actuated. compensating piston,

v means connected with said actuating piston for operation .thereby of said compensating piston, and means including a compensating'valvelever pivotally supportiedintermediate its ends by said compensating piston that acts to restore said lever to a preexisting position, said lever being connected at one end with said actuating piston, a compensating valve connected with said compensating valve lever to control operation of said compensating piston; a. pilot valve for controlling pressure to opposite sides of said actuating piston, a connection between the opposite end of said lever and said pilot valve and including said loosely disengageable members to permit movement ofsaid compensating mechanism independently of said pilot valve, and an opefativeconnection between said last mentioned connection and said centrifugally operated member.

6. A governor mechanismincluding a motor driven centrifugallyoperated member, a member for controllingsupply of an energizing-medium sating piston and connected at one end with said to said motor, and a connection between said members, said connection including loosely dis engageable members operating independently of each other and a pressure operated actuating piston operatively connected with said member for controlling supply of an energizing medium to said motor, a pressure actuated compensating piston, means connected withsaid actuating piston for operation thereby of saidcompensating piston, and means including a compensating valve lever pivotally supported intermediate its ends by said compensating piston that acts to restore said lever to a preexisting position, saidlever being connected at one end with said actuating piston, a compensating valveconnected with said compensating valve lever to control 7 operation of said compensating piston, a pilot valve for controlling pressure to opposite sides of said actuating piston, a connection between the ated member, a pressure operated actuating pistonconnected for operation by said relay for controlling supply of said energizing medium to said motor, said relay including an actuating piston, means for admitting pressure to opposite sides of said piston, and a double acting pilot valve shiftably mounted in and carried by said piston and operated thereby to control said admission of said pressure to either side ofsaidpiston or to be released therefrom, a pressure actuating compensating piston, means for actuating the latter, a compensating valve lever pivotally supported bysaid compensating piston and connected at one end with said actuating piston,a compensating valve connected with said compensating valve lever to control operation of said compensating piston, a pilot valve for controlling pressure to opposite sides of said actuating piston, and a connection between the opposite end of said lever and said pilot valve and including a valve actuating beam pivotally supported on said relay, 8. A governor mechanism including a motor driven centrifugally operated member, a member for controlling supply of an energizing medium to said motor, and a connection between said members, said connection including a pressure actu ated relay comprising a piston having a chamber therein with ports opening laterallytherefrom,

a double acting valve shiftably mounted in said chamber and carried by; said piston to control pressure on opposite sides of said piston and to release the pressure therefrom and a pressure "operated actuating piston operatively connected with said member foncontrolling supply of said medium to said motor, said connection including I a rod extending from said piston and pivotally v connected with said member for controlling supply of said medium to said motor, a pressure actuated compensating piston, compensating valve means for actuating thelatter, a compensating valve lever pivotally supported by said compen- 'rod and also connected with said compensating valve means, a pilot valve for controlling pressure to opposite sides of said actuating piston, a connection between the opposite end of said lever and said pilot valve, and an operative connection between said last mentioned connection and said centrifugaliy operated member.

9. A governor mechanism including a motor driven centrifugally operated membena member for controlling supply of an energizing medium to connected with said centrifugally operated member, said relay including a piston having a chamber therein with ports opening laterally therefrom a. double acting valve shiftablymounted in said chamber and carried by said piston to control pressure on opposite sides of said piston to release the pressure. therefrom and aconnection between saidrelay and said member for controlsaid motor, a pressure actuated relay operatively ling supply of said medium to said motor, said a connection including a pressure operated actuating piston, a stem projecting from said piston to said member for controlling supplybf said medium to 'said motor, a pressure actuated compensating piston, compensating valve means for actuating the latter, a compensating valve lever pivotally supported by said compensating piston and connected at one end with said stem and also connected with said compensating valve means for operation thereof, a pilot valve for controlling pressure on opposite sides of said actuating piston, a valve actuating beam pivotally supported by said relay and operatively connected atone end with said pilot valve, and an operative con- I nection between the other end'of said beam and said compensating valve lever.

10. A governor mechanism including a motor driven centrifugally operated member, a member,

for controlling supply of, an energizing medium to said motor, and a connection between said members, said connectionincluding a pressure actuatedrelay comprising a piston having a chamber therein with ports opening laterally therefrom, a double acting valve shiftably mounted in said chamber and carried by said piston to control pressure on opposite sides of said piston and to pensating-piston, means for actuating'the latter, a compensating valve'lever pivotally supported by said compensating piston and connected at oneend with said actuating piston, a pilot valve; -for controlling pressure to 'oppositesides of said actuating piston, a pilot valve for controlling admission of pressure to opposite sides of said compensating piston, a connection between the 0pposite end of said compensating valve lever. and

release the pressure thereiromand a pressure operated actuating piston ,operatively connected with saidmember for controlling supply of said mediumeto said motor, a pressure actuated com-' said last mentioned pilot valve, and an operative connection between said last, mentioned pilot valve and the first mentioned pilot valve. r

11. A governor mechanism including a motor driven centrifugally operated member,,a member for controlling supply of an energizing medium to said motor, and a connection between said members, said connection including a pressure actuated relay comprising a piston-having a chamber therein with ports opening laterally therefrom, a double acting valve shiftably mounted in said chamber and carried by said piston to control pressure on opposite sides of said piston and to release the pressure therefrom and a pressure operated actuating piston operatively connected with said member for controlling supply of said medium to said motor, a pressure actuated compensating piston, a compensating valve lever pivotally supported by said compensating piston and connected at one end with said actuating' piston, a pilot valve for controlling pressure to opposite sides of said actuating piston, a pilot valve for controlling pressure to'opposite sides of said compensating piston and pivotally connected to said compensating valve lever, a ported sleeve within which said last mentioned pilot valve is located, means for adjusting the position of said sleeve, a connection between the opposite end of said last mentioned pilot valve and the first mentioned pilot valve, and an operative connection between said last mentioned connection and said centrifugally operated member.

12. A governor mechanism including a motor driven centrifugally operated. member, a member so for-controlling supply of an energizing medium to said motor, and a connection between said members, said connection including a pressure actuated relay comprising apiston having a chamber therein with ports opening laterally g5 therefrom, a double acting valve shiftably mounted in said chamber and carried by said piston to control pressure on opposite sides of said piston and to release the pressure therefrom and a pressure operated actuating piston operatively con- 30 nected with said member for controlling supply of said medium to saidmotor, a pressure actuated compensating piston, a compensating: valve lever pivotally supported by said compensating piston and connected at one end with said actuating 85 piston, 'a-- pilot valve for controlling pressure to opposite sides of said actuating piston, a pilot I valve for controlling pressure to opposite sides of said compensating piston, a ported sleeve within which said last mentioned pilot valve is located,

40 a sleeve operating lever connected at one end with said sleeve and operatively connected at its opposite end with said actuating piston, and a valve actuating beam connected at one end with the valve located in said sleeve and at its opposite 5 end with the pilot valve for operating the actuating piston, said beam being operatively connected with said centrifugally operated member. 13. A governor mechanism including a motor driven centrifugally operated member, a member 5 for controlling supply of an energizing medium to said motor, and a connection between said members, said connection including a pressure actuated relay comprising a piston havinga chamber therein with ports opening laterally therefrom, a

55 double acting valve shiftably mounted in said chamber and carried by said piston to control pressure to opposite sides of said piston and to release the pressure therefrom and a pressure operated actuating piston, means connected with go said centrifugally operated member for regulating pressure applied to said actuating piston, a compensating piston connected with said actuating piston for operation thereby, a pilot valve for supplying fluid pressure to opposite sides of said compensating piston, and means in the passage between said pilot valve and compensating piston for regulating the supply of pressure to said compensating piston to control its rate of movement.

14. A governor mechanism including a motor driven centrifugally operated member, a device for controlling supply of an energizing medium to said motor, an operative connectionbetween said members, said connection including loosely disengageable members operating independently of each other and an actuating piston, means connected with said centrifugally operated member for controlling operation of said actuating piston, a compensating mechanism operatively connected with said actuating piston for operation thereby, said mechanism including a compensating piston, a compensating valve to control operation of said compensating piston, a compensating valve lever pivotally supported intermediate its ends by said compensating piston that acts to restore said lever to a preexisting position,

said lever being connected at one end with the tings at no load and at full load' throttle positions.

15. A governor mechanism including a motor driven centrifugal actuating device, a member for controlling the supply of an energizing medium to said motor, a. piston operatively connected with said member, a valve to control supply of pressure to opposite sides of said piston, an operating lever operatively and 'disengageably connected with said valve to operate it and also operatively connected with said actuating device for operation thereby, and an operative connection between one end of said lever and said piston for operation of said lever by said piston independently of said valve in a resetting operation.

16. A governor mechanism including a motor driven centrifugal actuating device, a member for controlling the supply of an energizing medium to said motor, a piston operatively connected with said member, a valve to control supply of pressure to opposite sides of said piston, an operating lever operatively and disengageably connected with said valve to operate it and also operatively connected with said actuating device for operation thereby, a second piston mounted in a pressure chamber, a lever pivotally mounted onsaid second piston and operatively connected at one end with the first mentioned piston and at its opposite end with a valve bearing rod, valves on said rod to control supply of pressure to said second piston, and an operative connection be 

